Under circumstances where a microphone is away from sound sources, when a plurality of sound sources are present, consideration is given to collecting sounds for individual sound sources in high quality. The microphone observes signals coming from the sound sources mixed in a space. For this reason, it is desirable that the signals be separated for each sound source, or that sound capture be performed while suppressing signals coming from other sound sources (noise sources) when a single sound source is targeted. To this end, signal processing techniques have been proposed to enhance a target speech using multichannel acoustic signals obtained by a microphone array, that is, a plurality of microphones.
In the conventional techniques, a variation in acoustic characteristics of a space, a deviation from an expected arrangement or sensitivity of microphones, and other factors, have decreased the accuracy of estimating the sound source in some cases.